Detector devices are used in seats in order to identify users on the seats (WO 2004/005068). It is also known to provide seats or the like with heaters in order to keep the user warm (DE 19724168 C1, WO 02/06083 A1). However, because the two functional systems have to be arranged as close as possible to the contact surface to work reliably and efficiently, under some circumstances they produce mutual interference.
For example, the temperature at the heating element must not become too high, because otherwise the measurement by the detector device would become incorrect. Therefore, more homogeneously heating and thus more expensive material must be used for the heating resistors. Simultaneously, heating elements would be thermally insulated by a detector device arranged simultaneously above these elements, and higher thermal output would actually be required. In addition, two simple systems, e.g., fixed to each other through adhesion, would cause the seat cushion to seem harder, and would require complicated positioning relative to each other.
Systems are known (DE 4338285, EP 0873903) in which an electric surface-heating element is used simultaneously as a sensor for the contact/use of a heated surface. This design, however, is difficult to realize from a metrological standpoint.
Heating elements (DE 10029237) are also known, which become electrically conductive in the area of loading when pressure is applied, and which locally heat this area. However, they supply no measurement signals to external devices.
There are other systems that arrange components of a heating element and a detector on a common carrier (WO 01/89267, DE 10057222). Such composite systems, however, are barely air permeable and require additional measures to shield the detector device from the heat conductors. In addition, defective parts are relatively expensive.
In addition, mat-like air-conditioning devices are known, e.g., from WO 02/053411 A2. A mat-like air-conditioning device has the advantage that it can be integrated easily into the production of the seat, in that it is placed on the completed seat cushion. Placement of the air-conditioning layer is thus independent of production of the actual cushion. In addition, the shape of the cushion is also nearly arbitrary, so that a single embodiment of a mat-like air-conditioning device can be used universally for many different seats. However, here there is the same problem in the simultaneous use of an air-conditioning layer and a seat occupancy detection device.
A vehicle seat is known from DE 19805174 that has air permeable cushioning. Heating elements are arranged in this cushioning. A fan blows air into the cushioning, circulates the air around the heating elements, and blows the heated air to the seat surface. The integration of such heating elements into the seat cushioning is complicated, however, and leads to the loss of comfort due to hardened sections in the cushion.
Thus, one problem is controlling/conditioning the temperature of surfaces in contact with users and simultaneously monitoring the use reliably; and here keeping the production costs moderate.